Temperature-Induced Variations in Photocatalyst Properties and Photocatalytic Hydrogen Evolution: Differences in UV, Visible, and Infrared Radiation

In this work, solar-heating-induced temperature-based photocatalytic hydrogen evolution reaction (PC-HER) of different photocatalysts (TiO2 P25, g-C3N4, and their loaded Pt) was comprehensively studied and analyzed with the assistance of a series of temperature-based in situ characterizations. It was found that pristine TiO2 P25 and g-C3N4 displayed enhanced PC-HER performances with increasing temperature (25–65 °C), while their loaded Pt nanoparticles (NPs) demonstrated a different behavior under ultraviolet (UV) or visible irradiation, presenting the highest hydrogen evolution rate at 35 °C. More interestingly, Pt NPs-g-C3N4 showed increasing PC-HER performances from 25 to 65 °C under visible light irradiation. Characterizations suggested that lowered electrical impedance, reduced band gap, increased light absorption, and elongated photoelectron lifetime with increased temperature are beneficial for improved PC-HER. However, agglomeration of Pt NPs significantly deteriorated the PC-HER performance at higher temperature and UV light can aggravate the thermal agglomeration of Pt NPs.